1. Field of the Invention
The present invention relates to an eye image tracking apparatus that can track images of the eyes more accurately by using image processing to retrieve and track images around the eyes as well as those of eyes themselves.
2. Description of the Related Art
A conventional eye image tracking apparatus for a driver of a vehicle is described, for example, in Japanese Patent Application Laid-Open No. 6-32154. The overall configuration of this apparatus comprises an image input means 51, a digitalizing means 52, an eyeball-existing-region setting means 53, an eyeball detection means 54, an eye-state detection means 55, and a driver condition determination means 56, as shown in a block diagram in FIG. 22.
The main flow of the operation of this apparatus is shown in FIG. 23. After the system has been activated, a timer is started at step S1. At step S2, the driver's face is photographed, and this image is converted into a digital signal, which is then stored in an image memory as input image data for a single frame at step S3. The input image data stored in the image memory is digitalized at step S4 to determine the horizontal and vertical widths of the first (i.e., right) and second (i.e., left) eyeball-existing-regions at step S5 and step S6. Then, the eyeballs are detected at step 7, and an eye state (i.e., opened or closed eye) is determined at step S8. The count of the timer having been started at step S1 is used in this step. The eyeball detection means 54 scans all the vertical pixels in each of the right and left eyeball-existing regions for each horizontal dot to retrieve the number of continuous black pixels in order to detect the eyeballs. Finally, it is determined whether or not the driver is dozing at step S9. After this series of processing, the process returns to step S2 to repeat this processing.
The regions in the image that are digitalized, however, are unstable due to the influences of the presence of the driver's glasses, the weather condition, and the direction of the driver's face. Since, however, the above-mentioned apparatus retrieves and tracks only the eyeballs within the eyeball-existing regions, it erroneously detects the driver's eyebrows or the frame of the glasses when missing the eyeballs due to the presence of the glasses or direct rays reflected from the lenses. In addition, it requires a long processing time because the eye-state detection means 55 tracks the eyeballs by scanning all the vertical pixels in each of the right and left eyeball-existing regions for each horizontal dot for each frame.